CSC Scientific Blog

A blog about test equipment

CSC Scientific Blog

Instrument Accuracy?  Is it only an illusion?

Posted by Art Gatenby on Aug 28, 2019 12:05:00 PM

Regularly I’m asked the question; “How accurate is this moisture balance?”

The questioner asks for the answer in terms of percent (%) moisture. When I answer “it depends”, I always get the unspoken response, “Why did I ask this stupid idiot?

Absolute Measurement

When you ask about the accuracy of something like weight or temperature the answers are straight forward and relate to the instruments' precision. For example 25 grams or 50 degrees plus or minus (+/-) 0.1 gram or 1/2 degree.  

Percent is Relative

When you ask the question of how accurate is my percentage reading, the answer becomes complicated. It’s complicated because percentage (%) is a relative term. For example, the answer for the result of a Loss on Drying (LOD) moisture test, is based on the size of the sample you use.

Using the example of a LOD moisture test we can understand the concept. The result of this type of test is calculated by subtracting the weight of the sample at the end of the test from the weight of the sample at the beginning of the test. This difference is divided by the initial weight of the sample. This procedure produces a % moisture result.

Sample Size

In the following analysis, the implication s of sample size and instrument precision will be illustrated. This will be based on a sample that has 23.5% moisture and an electronic LOD moisture balance that has a sensitivity of 0.001 grams and repeatability of ± .005 grams.

Sample Analysis

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Topics: Moisture Analysis, Moisture Testing, CSC Digital Moisture Balance, Loss-On-Drying, Moisture, moisture balance, instrument accuracy

Contact Angle Fundamentals: What You Actually Need to Know

Posted by Amanda Ranowsky on Aug 26, 2019 9:00:00 AM

It’s easy to pretend you know the operating terms surrounding contact angle measurement. But do you really? For industries such as coatings, printing, and oil recovery, contact angle testing is an essential component of the production and/or quality assurance process. Having a competent understanding of these terms will make it so much easier to choose the right instrument for your company - one you can be certain will do what you need it to do. 

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Topics: Surface Tension, contact angle, contact angle meter, dynamic contact angle, Liquid Properties

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